main/openrc: build with meson

one issue:
the 'tests' are not integrated into meson, and can't run with the separate output tree (./output), expecting everything built in-tree (like in the old makefile system.. not sure if they should be fixed or not, given how it's just two test files

meson options were set according to file output (with these, the files are all in the same places). they look different, but i guess this is just how they are used now.